Abstract : The purpose of this research was to evaluate the heat dissipation effectiveness of several silicon micromachined structures when applied to wafer scale integration modules. The thermal dissipation characteristics of four micromachined structures and two control surfaces were determined. The heat dissipation structures were incorporated into a wafer scale integration thermal module. The micromachined structures investigated include: randomly spaced and sized pyramids, deep-vertical-wall-grooves, V-grooves, and microfluid channels. This research effort found no evidence that the micromachined structures improved the thermal dissipation characteristics of the thermal modules when air (natural and forced) cooling was used. However, the presence of voids in the epoxy used fabricate the deep-vertical-wall-groove and pyramid thermal modules significantly degraded their thermal dissipation performance. A significant decrease in the thermal resistance occurred when water cooling was used with the micro-fluid channel structures.... Wafer scale integration, Integrated circuits, Thermal management, Silicon Micromachining, Thermal modules.